Cdc20/p55 mediates the resistance to docetaxel in castration-resistant prostate cancer in a Bim-dependent manner.

Abstract

At least to date, no effective treatment for advanced castration-resistant prostate cancer (CRPC) has been established. Recent studies indicated that cell division cycle 20 homolog (Cdc20) overexpression is associated with poor prognosis in patients with castration-resistant prostate cancer. However, the mechanism of Cdc20 in the development of docetaxel resistance in CRPC remains elusive. In this study, the transcription of Cdc20 was confirmed in three independent CRPC cell lines derived from different tissues, including LNCaP, PC3, and DU145. Docetaxel resistant (DR) cell lines were generated within the background of DU145 and PC3. The protein levels of Cdc20 and the biological phenotype were detected in both wild-type and DR cell lines. To further explore the mechanism of Cdc20 overexpression, stable cell lines with Cdc20 or Bcl-2 interacting mediator of cell death (Bim) deprivation were generated and examined for biological parameters. In addition, a specific Cdc20 inhibitor was used in DR cell lines to explore the potential solution for docetaxel resistant CRPC. Here, we identified Cdc20 is overexpressed in docetaxel resistant CRPC cell lines, including LNCaP, PC3, and DU145. We also reported that DR cell lines, which mimic the recurrent prostate cancer cells after docetaxel treatment, have higher levels of Cdc20 protein compared with the CRPC cell lines. Interestingly, the protein levels of Bim, an E3 ligase substrate of Cdc20, were decreased in DR cell lines compared with the wild-type, while the mRNA levels were similar. More importantly, in DR cell lines, the biological phenotype induced by Cdc20 deletion could be significantly reversed by the additional knockdown of Bim. As a result, docetaxel resistant prostate cancer cells treated with the pharmacological Cdc20 inhibitor became sensitive to docetaxel treatment. In conclusion, our data collectively demonstrated that Cdc20 overexpression facilitates the docetaxel resistant of the CRPC cell lines in a Bim-dependent manner. Furthermore, additionally targeting Cdc20 might be a promising solution for the treatment of the CRPC with docetaxel resistance.